My wife just realized that all my 'lectronics can actually help her

[duckduck]

Wife asks me to feel her forehead because she thinks she might have a fever. "I might have the 'rona!" No, she does not. Her forehead feels fine. "We don't have any working thermometers and who knows where all of batteries are?" she says. I tell her that as part of my new 'tronics hobby that I have organized all of the batteries in this little bin. I put the thermometer on my bench and I soon realize that the thermometer's little CR1225 has turned slightly negative, so it is toast. We don't have a replacement, so I use my DC power supply and little grippers to supply 3.0 V to the battery leads on the thermometer and it lights up and beeps. I hold the leads while she checks her temperature: 97.3 degrees F (36.3 degrees science). "Oh, thank God! I thought I was going to be hooked up to a ventilator for sure!" She looks over the bench and I can tell that she realizes that this 'lectronics stuff can actually come in handy.

Still struggling to demonstrate the great utility of the trials motorcycle and electric guitars.

[NiHaoMike]

I put the thermometer on my bench and I soon realize that the thermometer's little CR1225 has turned slightly negative, so it is toast.

If there's only one cell, what could have given it a reverse charge?

[pickle9000]

So you think you can wrangle that realization into some new tools for the test bench?

[Tom45]

To quote Red Green: If the women don't find you handsome, at least they will find you handy.

[babysitter]

Tell her if you can get a big enough lab, you might even build her a ventilator..

[duckduck]

I put the thermometer on my bench and I soon realize that the thermometer's little CR1225 has turned slightly negative, so it is toast.

If there's only one cell, what could have given it a reverse charge?

I don't know.

I googled this phenomenon and read that there's a theory that other batteries can "push" a battery negative. It seems to me that I find "negative" batteries in devices with a "soft" power switch more often than in devices with a power switch that breaks the circuit with the batteries. My gut feeling says that "negative" batteries are correlated with a long, low-current drain on the battery. I certainly have some "undead" batteries in my bucket-o-dead-batteries. I may just tape/solder a 100k R to a few batteries that are merely too low to power the super-low-cost electric motors in Junior's toys and then check them a few weeks later to see if they have joined the dark side.

The "negative" battery is a CR1225 lithium cell (3 V nominal) and it was in a thermometer with a "soft" power switch. "58" has been printed on the back of that cell.

N.B.: I'm one of the "haters" from the "I hate batteries" thread ( https://www.eevblog.com/forum/chat/i-hate-batteries/msg3002444/#msg3002444 ). Would I really prefer to have a mains-powered thermometer? Even if it were double-galvanically isolated, triple-insulated, and UL listed I would still not allow my family to use it, so batteries win again. Might be nice to get a thermometer that uses 3xAA ( https://www.welchallyn.com/en/products/categories/thermometry/oral-axillary-rectal-thermometers/suretemp-plus-692.html ), but for US$500 I'd just as soon buy a FLIR so I can see how I've miswired my latest project... 

EDIT: Henli Max batteries are made by YuFeng Electrical ( http://en.czyufeng.com/ ).

Changzhou Yufeng Electrical is a high-tech enterprise engaged in the R&D, production and sale of 3V primary lithium button cells. Our company has two factories, one is in Zhonglou District with an area of 12,000 square meters, and the other is in Changzhou Photovoltaic Industrial Park covering an area of 35,000 square meters. We also have eight industrial buildings, two office buildings and a staff dormitory building. We employ over 300 personnel and use the most advanced automatic assembly lines. Thus, our monthly output can reach 40 million batteries.
Currently, we have more than 20 technical patents. Moreover, we have passed ISO 9000:2005 and ISO 14001:2004 certifications. Our products are compliant with UL, RoHS, REACH and UN38.3 standards.